Or if it was, most officers shut off the radar while they're out of the car on a traffic stop or when using it in instant-on mode. With the radar off there was no signal to detect and your detector stayed quiet.

Other K-band false alarms are caused by traffic-sensing radar (TSR). These monitor traffic flow and volume.

Many newer detectors recognize TSR radar and some GPS-enabled models can lock out door-opener radar. BSM radar is harder to combat since the offending vehicles are in motion. GPS can't be used to counter it, but some detectors use software to deal with the problem.

Q: What's the best radar detector?

A. It used to be the one with the longest range. Now the best radar detector is the one that can filter out the junk while still alerting to real threats well in advance.

One of their attractions is the ratio of performance versus price—both are punching well above their weight class. The XP ($349) had longer range than a $499 Escort model. And the Pro M ($449) outperformed the $599 Escort Redline EX.

They have additional strategies to reduce false alarms. For example, both automatically adjust sensitivity based on speed—low when you're stuck in traffic, maximum at higher speeds when you're at risk.

Audi R8 Spyder equipped with remote detector and laser jammers. By design, there's not much to see.

Q: What's the attraction of a built in detector?

A. Security is one advantage; we've yet to have a remote (built-in) radar detector get stolen. Regardless of its value, if a radar detector is visible, eventually some twit will smash the glass and steal it.

Another advantage of remote models is discretion. Detectors are legal in 49 states, but some cops disapprove. Get stopped by an officer like this and you're more likely to be cited.

Escort Max ci main components.

Radenso has one remote, Escort offers several and K40 has one. All are available with laser jammers of varying effectiveness.

They're significantly higher in price than even the best windshield-mounted radar detector. For example, the top Escort windshield-mounted detector is the Passport Max 360c. Front and rear radar antennae allow its LED arrows to point toward threats. The Max 360c retails for $649.

In contrast, the least expensive Escort remote model with laser jammers is $3,000. Figure on another grand for installation.

Radar used in instant-on mode can give little advance warning.

Q: I typically drive 10 miles of back roads then 30 miles of the Pennsylvania Turnpike twice daily. What's the best way to set up my Radenso Pro M?

A. The State Police remains the only Pennsylvania law enforcement agency authorized to use radar, all of it K-band. Unfortunately, BSM (Blind Spot Monitoring) radar also uses K band.

For that reason you'll want to optimize K-band performance while minimizing false alarms. Some detectors, Radenso models included, have settings that can be tweaked to accomplish this. We explain the process in Radenso Pro M Performance Tips, a four-page guide we provide to our Pro M customers. Most manufacturers mention these options in the user manual.

Moving radar is tough to beat. This model can clock four of the five vehicles ahead of the cruiser.

Q: Does radar work if the patrol car is moving?

A. Yes and moving radar is far more lethal than stationary radar. Most of these radars have an antenna in front, another in back, giving them front-rear coverage.

They can also track same-direction vehicles in front of or behind the rolling cruiser. Many also can target the fastest car in a pack, making it hard to hide behind slower vehicles.

The most common encounter with moving radar is to meet an oncoming cruiser, pass it, and watch as the officer U-turns and whistles up behind you, light bar ablaze. He got your speed before you met, leaving no time to react; the show's already over.

Q: I've read that putting the detector up high on the windshield gives it better range. Is this true?

A. That would seem logical, but in 30 years of testing detectors we've never seen range improve by altering mounting height by a few feet.

An extra 50-plus feet might make a difference on rare occasions, but a radar detector is more affected by orientation than height. Keeping it level and pointed down the centerline of the vehicle will maximize range.

Escort Passport Solo S4

Q: I want a detector that runs on batteries so I won't have to deal with a power cord. How do they stack up against the rest?

A. There's only one cordless, the Escort Solo S4. It's traditionally been the best radar detector with cordless operation.

Although battery-powered, it can also use a power cord and run on the vehicle's electrical power.

But be prepared for lower performance, especially on the Ka band favored by state highway patrols. Good as it is, the Solo S4 has far less range than a similarly-priced corded model.

Q: Driving in California, I've never seen anything other than Ka band be a real alert. Am I safe turning off X and K bands unless/until I leave the state?

A. Shutting off X band west of the Mississippi is fine, but doing the same on K band isn't risk-free. Although the California Highway Patrol uses Ka band exclusively, several thousand K-band radar units remain in service nationwide, some of them on the West Coast.

But if you're being pestered by K-band false alarms, in your area the risk is low enough to make the move worthwhile.

Long range is the best protection against instant-on radar.

Q: On the highway, why does my detector alert sometimes when I don't see a cop car?

A. If it's an X- or K-band alert it may be an automatic door opener. The best radar detector can spot these from a half-mile away or more. A short K-band signal could well be from Blind Spot Monitoring radar in a nearby car.

If it's a Ka-band alert, most likely it's instant-on radar working traffic up ahead. With the radar on hold, the officer triggers it at close range and gets a speed almost instantly.

A. If you're driving with a high-performance detector you might already be getting camera warnings without knowing it.

Until recent years most red light and speed cameras were triggered by pavement sensors. With no radar present, there was nothing to detect.

The trend now is radar-control, much cheaper to install and maintain. Radar makes the cameras detectable and a few high-performance detectors with exceptional K-band sensitivity can spot them.

That's the good news. The bad news: there's so much nuisance radar around today that hypersensitivity on K band can make some detectors false-alarm incessantly.

Q: What's the best radar detector that will keep me from getting flashed by a red light camera?

A A GPS-enabled model is your best hope. Look for one with high sensitivity on Ka band, for long range. Also, good filtering to weed out junk radar and keep it quiet. Several of these were compared in a recent test.

The laser's pinpoint beam makes it extremely difficult to detect. The only defense is a laser jammer.

Q: Sometimes I drive by a cop aiming his radar gun at me and my detector doesn't go off. How come?

A. If he was peering through an aiming reticle it was a laser, not radar. The pinpoint beam is nearly impossible to detect and allows one car inside a pack to be clocked. The only defense is a laser jammer.

Jammers are illegal in 14 states, but many drivers are willing to chance a minor infraction in exchange for dodging a far more expensive speeding ticket.

A. We've yet to test one that jams anything. Not that you'd want to use a radar jammer, given that it's a federal felony even to possess one.

We broke the story about Rocky Mountain Radar in 1993 [The Little Jammer That Couldn't, Automobile Magazine] and have tested many of its wares in the years since. Aside from being marginal at detecting radar, none exhibited any jamming effect on radar or lasers. Learn more

On the other hand, laser jammers are legal in 26 states. But they're way too big to fit inside a windshield-mounted radar detector. Two or more jammers are mounted in the grille area to protect the headlights—and front plate if so equipped—an officer's favorite aimpoint. Learn more about laser jammers.